Splitting a bill and working out a tip is the kind of math that always seems to land when everyone is full and nobody wants to think. A quick method — or a calculator — saves the table from the awkward shuffle.
TL;DR — Enter the bill, slide to a tip percent, and set the number of people in the tip calculator to get the total and the per-person split.
How much to tip
In the US, the usual range for table service is 15% to 20%, with 18% a comfortable middle. Exceptional service might earn more; poor service less. Counter service, takeout and delivery each have their own norms, generally lower than full table service. Outside the US, tipping customs vary widely — in some countries service is already included.
The mental shortcut
To tip roughly 20%, take 10% of the bill (just move the decimal one place) and double it. A $80 bill: 10% is $8, double it for a $16 tip. For 15%, take that 10% and add half of it again. It is close enough for a restaurant and quick enough to do before the card machine arrives.
Splitting fairly
Once you have the total with tip, dividing by the number of people gives the per-person share. The tip calculator does the tip, the total and the split in one step — and shows the tip per person too, which is handy when everyone is chipping in separately.